title: A minimally invasive assay for individual assessment of the ATM/CHEK2/p53 pathway activity.
abstract: Ionizing radiation induces DNA Double-Strand Breaks (DSBs) which activate the ATM/CHEK2/p53 pathway leading to cell cycle arrest and apoptosis through transcription of genes including CDKN1A (p21) and BBC3 (PUMA). This pathway prevents genomic instability and tumorigenesis as demonstrated in heritable syndromes [e.g. Ataxia Telangiectasia (AT); Li-Fraumeni syndrome (LFS)]. Here, a simple assay based on gene expression in peripheral blood to measure accurately ATM/CHEK2/p53 pathway activity is described. The expression of p21, Puma and Sesn2 was determined in blood from mice with different gene copy numbers of Atm, Trp53 (p53), Chek2 or Arf and in human blood and mitogen stimulated T-lymphocyte (MSTL) cultures from AT, AT carriers, LFS patients, and controls, both before and after ex vivo ionizing irradiation. Mouse Atm/Chek2/p53 activity was highly dependent on the copy number of each gene except Arf. In human MSTL, an AT case, AT carriers and LFS patients showed responses distinct from healthy donors. The relationship between gene copy number and transcriptional induction upon radiation was linear for p21 and Puma and correlated well with cancer incidence in p53 variant mice. This reliable blood test provides an assay to determine ATM/CHEK2/p53 pathway activity and demonstrates the feasibility of assessing the activity of this essential cancer protection pathway in simple assays. These findings may have implications for the individualized prediction of cancer susceptibility.
authors.affiliation: Biological Effects Department, Centre for Radiation Chemical and Environmental Hazards, Health Protection Agency, Didcot, Oxfordshire, UK.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Kabacik
authors.forename: Ana
authors.initials: A
authors.lastname: Ortega-Molina
authors.forename: Alejo
authors.initials: A
authors.lastname: Efeyan
authors.forename: Paul
authors.initials: P
authors.lastname: Finnon
authors.forename: Simon
authors.initials: S
authors.lastname: Bouffler
authors.forename: Manuel
authors.initials: M
authors.lastname: Serrano
authors.forename: Christophe
authors.initials: C
authors.lastname: Badie
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000097:blood; D001260:Ataxia Telangiectasia / Q000097:blood / Q000378:metabolism; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D064447:Checkpoint Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000097:blood; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004198:Disease Susceptibility / Q000097:blood / Q000378:metabolism*; D018628:Gene Dosage / Q000235:genetics; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D016864:Li-Fraumeni Syndrome / Q000097:blood / Q000378:metabolism; D051379:Mice; D009369:Neoplasms / Q000175:diagnosis*; D009687:Nuclear Proteins / Q000097:blood; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000097:blood; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000502:physiology*; D013601:T-Lymphocytes / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D000084622:Sestrins
chemical_list: D051017:Apoptosis Regulatory Proteins; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D064447:Checkpoint Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C438378:BBC3 protein, human; C465398:SESN2 protein, human; D000084622:Sestrins; C576324:ATM protein, human; C576325:Atm protein, mouse; C578634:CHEK2 protein, human; C578633:Chek2 protein, mouse